The present invention relates to methods of, and apparatus for, remotely controlling the function of electronic or electromechanical appliances.
Appliances equipped with remote control capability are now commonplace, and have proved very popular as they enable the operator of the appliance to effect changes in the operation of the appliance without having to come into physical contact with it. For extra convenience, modern remote control systems do not require an electrical connection between controller and appliance, signalling being achieved by means of suitably-modulated ultrasonic, radiofrequency or infra-red energy. Functions achievable using appliance remote controls include selections of tracks to be played from a compact disk, starting or stopping recording of a video tape recorder, selection of channel on a television receiver, and so on.
Although prior-art infra-red or ultrasonic remote control schemes operate satisfactorily over small distances, usually within the same room as the controlled appliance, it is not possible to operate appliances over great distances. For example it is not possible to start a video recorder from an office several kilometers distant.
Some appliances have been made utilising radio remote control, which permits operation over larger distances, but ultrasonic or infra-red systems are almost universally are far more popular as these systems do not suffer the problem of interference between controllers which often occurs using a radio system. As a result, it is not possible to control the majority of appliances over large distances using the supplied controller.
The present invention overcomes this limitation, providing means and method for controlling commonly-available appliances over large distances without need to modify the appliance.
According to the present invention there is provided a method of electronic appliance remote control capable of operation of appliances over unlimited distances, comprising the steps of transmitting a control signal from a distant control point, receiving and demodulating said control signal, reformatting said demodulated signal to correspond to control codes suitable for reception by the remote-control input of an appliance to be controlled (said input being for example the standard infra-red remote control receiver of a domestic appliance), and transmitting said code to the appliance to be controlled.
In another aspect the invention consists in long-distance remote control apparatus, receiving means equipped to receive and demodulate a control signal from a control signal transmitter, a controller equipped to reformat said demodulated control signal to correspond to a control code suitable for transmission to an appliance to be controlled, and transmission means for transmitting said code to an appliance to be controlled.
An additional inventive feature which may be included with advantage, is the provision of means for automatically modifying the control code sent to the appliance on receipt of a radio signal conditional upon the current operational condition of the appliance. This feature is of particular benefit in cases where the control means of the appliance to be controlled has been designed assuming that the operator will be in close proximity to the appliance, and will therefore be able to take into account its current operational condition when pressing a button to achieve a desired action. For example, many video tape recorders (VTRs) utilise a remote control scheme whereby channel selection is achieved by two buttons, one of which causes the channel number to increase, the other of which causes the channel number to decrease. To select a given channel it is therefore necessary to know which channel is currently selected, so that the requisite number of increase or decrease commands can be issued.